Arctic Amplification
Ice-albedo feedback, lapse rate, and polar vortex weakening
Arctic warms 3–4× faster than the global mean due to multiple feedbacks:
(1) Ice-albedo: melting ice exposes dark ocean, absorbing more SW radiation.
(2) Lapse rate: polar atmosphere warms more at surface (trapped heat), tropical atmosphere warms aloft.
(3) Polar vortex weakening: reduced temperature gradient weakens the stratospheric vortex,
allowing cold Arctic air to spill southward — "Wavy jet stream" pattern.